The purpose of this application is to request continued support for an already established laboratory devoted to the experimental study of neurophysiological mechanisms mainly at the cellular level by means of ultrastructural, biochemical, pharmacological and electrophysiological studies. Studies on invertebrate and marine organisms receive particular attention to take advantage of the rich local fauna. An important part of the laboratory's efforts is directed to study the nature and mechanism of action of toxins and other biologically active compounds produced by those organisms.